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Poly(ethylene terephthalate) (PET) is the most abundant polyester plastic and is causing serious environmental pollution. Rapid biological depolymerization of PET waste at a large scale requires powerful engineered enzymes with excellent performance. Here, we designed a computational strategy to analyze the ligand affinity energy of enzymes to PET chains by molecular docking with the dynamic protein conformations, named affinity analysis based on dynamic docking (ADD). After three rounds of protein engineering assisted by ADD, we drastically enhanced the PET-depolymerizing activity of leaf-branch-compost cutinase (LCC). The best variant LCC-A2 depolymerized >90% of the pretreated, postconsumer PET waste into corresponding monomers within 3.3 h at 78 °C, and over 99% of the products was terminal depolymerization products (terephthalic acid and ethylene glycol), representing the fastest PET depolymerization rate reported to date in the bioreactor under optimal condition. Structural analysis revealed interesting features that improved the ligand affinity and catalytic performance. In conclusion, the proposed strategy and engineered variants represent a substantial advancement of the biological circular economy for PET.
Zheng et al. (Wed,) studied this question.